lkml.org 
[lkml]   [2002]   [Sep]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: Uptime timer-wrap
On Sep 05, 2002  16:16 -0400, Richard B. Johnson wrote:
> I tried to simulate your observation by making a driver that
> set the 'jiffies' count upon an 'open'. The idea was to get
> the jiffies count to something close to wrap so I didn't have to
> wait a long time.
>
> Anyway, I found that setting the jiffies count to more than a
> few hundred counts into the future, causes the machine to halt
> with no interrupts (no Capslock, no NumLock, no network ping, etc).
>
> The machine just stops and I don't understand why.
>
>
> spin_lock_irqsave(&xlock, flags);
> jiffies += 0x1000;
> spin_lock_irqrestore(&xlock, flags);
>
> ... works just fine, but, changing 0x1000 to 0x7fffffff causes
> the machine to stop as reported.
>
> Does anybody have a clue?

Yes, because now some kernel code is going to wait 147 days - 1s
or something like that to finish.

See Tim Schmielau <tim@physik3.uni-rostock.de> patch for testing jiffies
wrap. It _initializes_ jiffies to a high pre-wrap value, maybe 5
minutes before wrap, instead of playing around with the jiffies value
after the system is running.

Cheers, Andreas
--
Andreas Dilger
http://www-mddsp.enel.ucalgary.ca/People/adilger/
http://sourceforge.net/projects/ext2resize/

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:28    [W:0.080 / U:0.580 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site